I have long considered surface bonded concrete block as the go to building method for below grade walls. After reading through all of the earthship books, I am now more interested in using local and less resource intensive materials than concrete block. Has anyone had success with earthbag/super adobe/hyper adobe or other rammed earth methods for underground or earth bermed structural walls? This would be for a northern climate where frost heave and freeze thaw cycles are a regular concern.
My building views are not as natural as most here Jeremy but I think CMU is a fine choice for below grade walls. They are affordable, light, easy to install, familiar to building trades and accepted readily by building codes. As for their environmental drawbacks, they are not as energy intensive as regular concrete although you probably need to fill the cells with regular concrete. Most CMU and some concrete include a measurable amount of coal fly ash with is helpful for the environment.
When you consider the extreme amounts of on-site labor that go into earthen walls, the fuel needed for calories and laborer transport can be significant variables in the environmental equation. In my opinion, water management details are easier with CMU than earthen walls.
"If you want to save the environment, build a city worth living in." - Wendell Berry